/*	$OpenBSD: poll.c,v 1.2 2002/06/25 15:50:15 mickey Exp $	*/

/*
 * Copyright 2000-2003 Niels Provos <provos@citi.umich.edu>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#ifndef HAVE_CONFIG_H
#include <config.h>
#endif

#include <sys/types.h>
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#else
#include <sys/_time.h>
#endif
#include <sys/queue.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#ifdef CHECK_INVARIANTS
#include <assert.h>
#endif

#include <event.h>
#include <event-internal.h>
#include <evsignal.h>
#include <log.h>

struct pollop
  {
    int event_count;		/* Highest number alloc */
    int nfds;                       /* Size of event_* */
    int fd_count;                   /* Size of idxplus1_by_fd */

    struct pollfd *event_set;

    struct event **event_r_back;

    struct event **event_w_back;
    int *idxplus1_by_fd; /* Index into event_set by fd; we add 1 so
			      * that 0 (which is easy to memset) can mean
			      * "no entry." */
  };

void *poll_init	(struct event_base *);
int poll_add		(void *, struct event *);
int poll_del		(void *, struct event *);
int poll_dispatch	(struct event_base *, void *, struct timeval *);
void poll_dealloc	(struct event_base *, void *);

const struct eventop pollops =
  {
    "poll",
    poll_init,
    poll_add,
    poll_del,
    poll_dispatch,
    poll_dealloc,
    0
  };

void *
poll_init (struct event_base *base)
{

  struct pollop *pollop;

  /* Disable poll when this environment variable is set */

  if (getenv ("EVENT_NOPOLL") )
    return (NULL);

  if (! (pollop = calloc (1, sizeof (struct pollop) ) ) )
    return (NULL);

  evsignal_init (base);

  return (pollop);
}

#ifdef CHECK_INVARIANTS
static void
poll_check_ok (struct pollop *pop)
{
  int i, idx;

  struct event *ev;

  for (i = 0; i < pop->fd_count; ++i)
    {
      idx = pop->idxplus1_by_fd[i] - 1;

      if (idx < 0)
        continue;

      assert (pop->event_set[idx].fd == i);

      if (pop->event_set[idx].events & POLLIN)
        {
          ev = pop->event_r_back[idx];
          assert (ev);
          assert (ev->ev_events & EV_READ);
          assert (ev->ev_fd == i);
        }

      if (pop->event_set[idx].events & POLLOUT)
        {
          ev = pop->event_w_back[idx];
          assert (ev);
          assert (ev->ev_events & EV_WRITE);
          assert (ev->ev_fd == i);
        }
    }

  for (i = 0; i < pop->nfds; ++i)
    {

      struct pollfd *pfd = &pop->event_set[i];
      assert (pop->idxplus1_by_fd[pfd->fd] == i + 1);
    }
}

#else
#define poll_check_ok(pop)
#endif

int
poll_dispatch (struct event_base *base, void *arg, struct timeval *tv)
{
  int res, i, msec = -1, nfds;

  struct pollop *pop = arg;

  poll_check_ok (pop);

  if (tv != NULL)
    msec = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;

  nfds = pop->nfds;

  res = poll (pop->event_set, nfds, msec);

  if (res == -1)
    {
      if (errno != EINTR)
        {
          event_warn ("poll");
          return (-1);
        }

      evsignal_process (base);

      return (0);
    }

  else if (base->sig.evsignal_caught)
    {
      evsignal_process (base);
    }

  event_debug ( ("%s: poll reports %d", __func__, res) );

  if (res == 0)
    return (0);

  for (i = 0; i < nfds; i++)
    {
      int what = pop->event_set[i].revents;

      struct event *r_ev = NULL, *w_ev = NULL;

      if (!what)
        continue;

      res = 0;

      /* If the file gets closed notify */
      if (what & (POLLHUP | POLLERR) )
        what |= POLLIN | POLLOUT;

      if (what & POLLIN)
        {
          res |= EV_READ;
          r_ev = pop->event_r_back[i];
        }

      if (what & POLLOUT)
        {
          res |= EV_WRITE;
          w_ev = pop->event_w_back[i];
        }

      if (res == 0)
        continue;

      if (r_ev && (res & r_ev->ev_events) )
        {
          event_active (r_ev, res & r_ev->ev_events, 1);
        }

      if (w_ev && w_ev != r_ev && (res & w_ev->ev_events) )
        {
          event_active (w_ev, res & w_ev->ev_events, 1);
        }
    }

  return (0);
}

int
poll_add (void *arg, struct event *ev)
{

  struct pollop *pop = arg;

  struct pollfd *pfd = NULL;
  int i;

  if (ev->ev_events & EV_SIGNAL)
    return (evsignal_add (ev) );

  if (! (ev->ev_events & (EV_READ | EV_WRITE) ) )
    return (0);

  poll_check_ok (pop);

  if (pop->nfds + 1 >= pop->event_count)
    {

      struct pollfd *tmp_event_set;

      struct event **tmp_event_r_back;

      struct event **tmp_event_w_back;
      int tmp_event_count;

      if (pop->event_count < 32)
        tmp_event_count = 32;
      else
        tmp_event_count = pop->event_count * 2;

      /* We need more file descriptors */
      tmp_event_set = realloc (pop->event_set,
                               tmp_event_count * sizeof (struct pollfd) );

      if (tmp_event_set == NULL)
        {
          event_warn ("realloc");
          return (-1);
        }

      pop->event_set = tmp_event_set;

      tmp_event_r_back = realloc (pop->event_r_back,
                                  tmp_event_count * sizeof (struct event *) );

      if (tmp_event_r_back == NULL)
        {
          /* event_set overallocated; that's okay. */
          event_warn ("realloc");
          return (-1);
        }

      pop->event_r_back = tmp_event_r_back;

      tmp_event_w_back = realloc (pop->event_w_back,
                                  tmp_event_count * sizeof (struct event *) );

      if (tmp_event_w_back == NULL)
        {
          /* event_set and event_r_back overallocated; that's
           * okay. */
          event_warn ("realloc");
          return (-1);
        }

      pop->event_w_back = tmp_event_w_back;

      pop->event_count = tmp_event_count;
    }

  if (ev->ev_fd >= pop->fd_count)
    {
      int *tmp_idxplus1_by_fd;
      int new_count;

      if (pop->fd_count < 32)
        new_count = 32;
      else
        new_count = pop->fd_count * 2;

      while (new_count <= ev->ev_fd)
        new_count *= 2;

      tmp_idxplus1_by_fd =
        realloc (pop->idxplus1_by_fd, new_count * sizeof (int) );

      if (tmp_idxplus1_by_fd == NULL)
        {
          event_warn ("realloc");
          return (-1);
        }

      pop->idxplus1_by_fd = tmp_idxplus1_by_fd;

      memset (pop->idxplus1_by_fd + pop->fd_count,
              0, sizeof (int) * (new_count - pop->fd_count) );
      pop->fd_count = new_count;
    }

  i = pop->idxplus1_by_fd[ev->ev_fd] - 1;

  if (i >= 0)
    {
      pfd = &pop->event_set[i];
    }

  else
    {
      i = pop->nfds++;
      pfd = &pop->event_set[i];
      pfd->events = 0;
      pfd->fd = ev->ev_fd;
      pop->event_w_back[i] = pop->event_r_back[i] = NULL;
      pop->idxplus1_by_fd[ev->ev_fd] = i + 1;
    }

  pfd->revents = 0;

  if (ev->ev_events & EV_WRITE)
    {
      pfd->events |= POLLOUT;
      pop->event_w_back[i] = ev;
    }

  if (ev->ev_events & EV_READ)
    {
      pfd->events |= POLLIN;
      pop->event_r_back[i] = ev;
    }

  poll_check_ok (pop);

  return (0);
}

/*
 * Nothing to be done here.
 */

int
poll_del (void *arg, struct event *ev)
{

  struct pollop *pop = arg;

  struct pollfd *pfd = NULL;
  int i;

  if (ev->ev_events & EV_SIGNAL)
    return (evsignal_del (ev) );

  if (! (ev->ev_events & (EV_READ | EV_WRITE) ) )
    return (0);

  poll_check_ok (pop);

  i = pop->idxplus1_by_fd[ev->ev_fd] - 1;

  if (i < 0)
    return (-1);

  /* Do we still want to read or write? */
  pfd = &pop->event_set[i];

  if (ev->ev_events & EV_READ)
    {
      pfd->events &= ~POLLIN;
      pop->event_r_back[i] = NULL;
    }

  if (ev->ev_events & EV_WRITE)
    {
      pfd->events &= ~POLLOUT;
      pop->event_w_back[i] = NULL;
    }

  poll_check_ok (pop);

  if (pfd->events)
    /* Another event cares about that fd. */
    return (0);

  /* Okay, so we aren't interested in that fd anymore. */
  pop->idxplus1_by_fd[ev->ev_fd] = 0;

  --pop->nfds;

  if (i != pop->nfds)
    {
      /*
       * Shift the last pollfd down into the now-unoccupied
       * position.
       */
      memcpy (&pop->event_set[i], &pop->event_set[pop->nfds],
              sizeof (struct pollfd) );
      pop->event_r_back[i] = pop->event_r_back[pop->nfds];
      pop->event_w_back[i] = pop->event_w_back[pop->nfds];
      pop->idxplus1_by_fd[pop->event_set[i].fd] = i + 1;
    }

  poll_check_ok (pop);

  return (0);
}

void
poll_dealloc (struct event_base *base, void *arg)
{

  struct pollop *pop = arg;

  evsignal_dealloc (base);

  if (pop->event_set)
    free (pop->event_set);

  if (pop->event_r_back)
    free (pop->event_r_back);

  if (pop->event_w_back)
    free (pop->event_w_back);

  if (pop->idxplus1_by_fd)
    free (pop->idxplus1_by_fd);

  memset (pop, 0, sizeof (struct pollop) );

  free (pop);
}
